The speeding was certainly naughty, but they didn't abuse your car, at least not physically. They were well under the limit pretty much the whole time (before and after they noticed the camera). Who cares what the service guys think? It's your car, if you like it, who gives a crap what anyone else thinks?
Is a test drive part of normal service procedure? I assumed it was, but if it wasn't, and they were just joyriding, that's a huge no no.
Also, thanks for the dash cam recommendation. I've been looking for ages and your setup looks pretty sweet.
